JP2598518Y2 - Internal combustion engine piston - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston for an internal combustion engine.

[0002]

2. Description of the Related Art A piston of an internal combustion engine reciprocates in a cylinder by an explosive force due to combustion, and transmits this force to a crankshaft via a connecting rod. Generally, a crown portion, a ring land portion, and a skirt portion are used. , And a pin boss portion.

A piston of this type is known, for example, from US Pat. No. 4,987,866. This piston has a substantially linear concave portion on the outer surface of the skirt portion between the pin mounting hole and the ring land portion,
The recesses reduce the stress applied to the periphery of the crown during combustion.

[0004]

However, since the concave portion of the piston is substantially straight, the piston cannot follow the deformation of the piston pin which flexes up and down due to combustion pressure and inertia. For this reason, an excessive surface pressure is easily generated between the piston pin and the pin boss.

That is, in the prior art, a concave portion is provided above the pin mounting hole, but the concave portion is formed in a substantially linear or substantially rectangular shape corresponding to the space between the oil holes of the oil ring groove. It has just been done. Therefore, the rigidity of the skirt around the pin mounting hole does not decrease, and it is impossible to follow the deformation of the piston pin.

For this reason, in the conventional piston, the surface pressure between the outer peripheral surface of the end portion of the piston pin and the inner peripheral surface of the pin boss portion due to deformation of the piston pin cannot be reduced. The occurrence cannot be prevented.

[0007]

Accordingly, the present invention provides a skater.
On the outer surface of the port, separate from each pin mounting hole
A continuous recess around the entire circumference of each mounting hole.
By providing a part, the outer periphery of the pin mounting hole
Reduce the rigidity and add the shape of the pin mounting hole to the piston pin.
Therefore, it was decided to deform. That is, according to the present invention
The piston of the internal combustion engine has a cylindrical shape provided under the crown
Of the skirt and the inner side of the skirt are provided facing each other.
Pin bosses provided on each of the pin bosses.
Internal combustion engine having pin mounting holes for supporting both ends of ton pin
In piston Seki, an outer surface of the skirt over DOO portion,
Separate from each pin mounting hole, around the pin mounting hole,
A continuous recess is provided over the entire circumference of each pin mounting hole.
It is characterized by.

[0008] In the configuration of claim 2, the lower part of the crown is
A cylindrical skirt provided and an inner surface of the skirt
Pin boss portions provided opposite to each other and the respective pin boss portions
Pin mounting holes that are provided at both ends and support both ends of the piston pin
The piston of the internal combustion engine comprising:
On the outer surface side of the portion, around each pin mounting hole,
A continuous recess is formed over the entire circumference of the
Characterized in that a cylindrical part is formed on the outer peripheral side of the outer opening of
doing.

Further, in the structure of claim 3, the lower side of the crown portion.
And a cylindrical skirt portion provided in the skirt portion.
A pin boss portion provided opposite to the surface side;
Pin mounting that is provided on the part and supports both ends of the piston pin
A piston of an internal combustion engine having
Around the pin mounting holes on the outer surface of the
Make the continuous concave part a depth dimension less than the thickness of the skirt.
It is characterized by being formed by.

[0010]

The pin recess is separated from the pin mounting hole by the pin mounting hole.
Around the perforated hole, continuous around the entire perimeter of each pin mounting hole.
By providing the pin on the outer surface side of the skirt, the rigidity around the outer opening of each pin mounting hole is reduced. Therefore, when both ends of the piston pin bend upward due to inertial force, the skirt portion between the concave portion and the pin mounting hole is deformed in accordance with the deformation of the piston pin, and the shape of the pin mounting hole is changed by the deformation of the piston pin. , The surface pressure generated between the piston pin and the pin boss decreases.

Further, according to the configuration of claim 2, the above-mentioned claim 1 is provided.
The same operation as described above occurs.

Further, in the configuration of claim 3, the above-mentioned claim is provided.
The same operation as that of 1 is performed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a front view of a piston according to a first embodiment of the present invention. A piston 1 reciprocating in a cylinder is provided with a combustion chamber between the piston 1 and a cylinder head. ) Is formed into a substantially closed cylindrical shape by a substantially disk-shaped crown portion 2 defining the above, a ring land portion 3 and a skirt portion 7 described below, and is formed of, for example, an aluminum alloy.

The ring land portion 3 is provided integrally below the crown portion 2 and includes a first ring groove 4, a second ring groove 5,
Third ring grooves 6 are formed spaced apart in the axial direction.
A compression ring is mounted on the first ring groove 4 and the second ring groove 5, and an oil ring (both not shown) is mounted on the third ring groove 6 at the lowermost stage.

The skirt portion 7 is provided integrally below the ring land portion 3 and is formed in a thin cylindrical shape. As shown in the sectional view of FIG. 2, a pair of pin boss portions 8 and 8 are formed on the inner surface 7A of the skirt portion 7 so as to face inward and face each other. A pin mounting hole 9 is formed in each of the pin boss portions 8. Have been. Each pin boss 8 supports the piston pin 10 by fixing both ends of the piston pin 10 inserted into the pin mounting hole 9 with a snap ring 11. Further, each pin boss 8 is formed such that the axial center C of the piston pin 10 is offset from the center line OO of the piston 1 toward the thrust side by a dimension d.

Each of the concave portions 12 is formed on the outer surface 7B of the skirt portion 7 so as to surround the entire periphery of each of the pin mounting holes 9.
The skirt 7 is recessed with a depth h that is equal to or less than the thickness of the skirt 7. That is, each of the recesses 12 and 12 is
Around the pin mounting hole 9, over the entire circumference of each pin mounting hole 9.
It is formed continuously . Each of these recesses 12 is formed apart from the outer opening 9A of each pin mounting hole 9, whereby the cylindrical portion having the thickness t is formed over the entire circumference of the outer opening 9A of each pin mounting hole 9. 13 are formed.

Reference numeral 14 denotes a connecting rod attached to the center of the piston pin 10 in the axial direction.

Next, the operation of the piston 1 of the internal combustion engine according to this embodiment will be described.

When the engine is started and the piston 1 reaches the top dead center, the piston pin 10 is displaced at both ends higher than the center by the inertial force of the piston 1 trying to ascend further. Deforms into a bowed downward shape.

Here, a recess 12 is formed on the outer surface 7B of the skirt portion 7 so as to surround the entire periphery of each pin mounting hole 9, and this recess 12 allows the outer opening 9A of each pin mounting hole 9 to be formed. Since the cylindrical portion 13 is formed on the outer periphery, the rigidity of the outer surface 7B of the skirt portion 7 around the outer opening 9A is partially reduced. Therefore, the piston pin 1
When 0 is deformed, the cylindrical portion 13 is also deformed upward by this deforming force, so that the shape of the pin mounting hole 9 follows the deformation of the piston pin 10.

Also, when the temperature of the piston 1 rises due to combustion and thermal deformation occurs due to thermal expansion, the piston pin 10 is deformed in a downward arcuate shape similarly to the case of the inertial force described above. Also in this case, since the cylindrical portion 13 is displaced upward according to the deformation of the piston pin 10, the pin mounting hole 9
Follows the deformation of the piston pin 10.

On the other hand, when the crown 2 receives the combustion pressure due to combustion, the piston 1 is pressed downward, so that both ends of the piston pin 10 are lower than the center, contrary to the case of the inertial force. Displaced to the side and deformed into an upward bow shape.

The recess 12 according to the present embodiment is formed so as to surround not only the upper half circumference of the pin mounting hole 9 but also the lower half circumference, that is, the entire circumference of the pin mounting hole 9. The cylindrical part 13 can also be displaced downward. Therefore, when both ends of the piston pin 10 are displaced downward, the cylindrical portion 13 is also deformed downward by this deforming force, and the shape of the pin mounting hole 9 follows the shape of the piston pin 10.

As described above, according to this embodiment, the concave portion 12 is formed on the outer surface 7B of the skirt portion 7 so as to surround the entire circumference of each pin mounting hole 9, and the outer opening of each pin mounting hole 9 is formed. Since the cylindrical portion 13 is formed on the outer peripheral side of the portion 9A, the rigidity of the outer surface 7B of the skirt portion 7 near the upper half circumference and the lower half circumference of the outer opening 9A can be partially reduced. .

Thus, when the piston pin 10 is deformed in a bow shape due to inertial force or the like, each cylindrical portion 13 is deformed upward so that the shape of the pin mounting hole 9 follows the deformation of the piston pin 10. Can be done. On the other hand, when the piston pin 10 is deformed in an upward bow shape by the combustion pressure, the shape of the pin mounting hole 9 is changed by deforming each cylindrical portion 13 downward.
0 can be made to follow.

As a result, the surface pressure generated between the outer surfaces of both ends of the piston pin 10 and the pin mounting hole 9 can be significantly reduced, the sliding resistance can be reduced, and the occurrence of the seizure phenomenon can be prevented. it can.

Next, a second embodiment of the present invention will be described with reference to FIGS.
It will be described based on. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

The recesses 21 and 21 are provided on the outer surface 7 of the skirt 7.
B is formed above the horizontal line Hc-Hc passing through the axial center C of the piston pin 10 so as to surround the upper half circumference of each pin mounting hole 9.

Each recess 21 is located above the outer opening 9A of each pin mounting hole 9 (the offset center line X in FIG. 3).
It is formed so as to approach at the upper side (along -X) and to be separated from the left and right sides (the horizontal line Hc-Hc direction) of the outer opening 9A. Further, as shown in the sectional view of FIG. 4, the outer opening 9A side of each recess 21 is formed on the outer surface 7B of the skirt portion 7.
And is formed in a tapered shape that is inclined upward at an angle θ while going inward in the radial direction of the piston 1.

A semi-cylindrical portion 22 is formed in the upper half of each pin mounting hole 9 by each recess 21. Each of the semi-cylindrical portions 22 has a small thickness t _{1 above} the outer opening 9 </ b> A of each pin mounting hole 9, and a thickness t _{2 in} the left-right direction along a horizontal line Hc-Hc passing through the axial center C of the piston pin 10. Is formed to be thick, and the outer surface 7B of the skirt portion 7 is formed.
It is formed in a semi-conical cylindrical shape so that the wall thickness gradually increases from the inside toward the inside.

In the present embodiment thus configured, the same operation and effects as those of the above-described first embodiment can be obtained with respect to the deformation of the piston pin 10 due to inertial force and thermal deformation. In addition, in this embodiment, in the present embodiment, each recess 21 is formed so as to be close to the upper side of the outer opening 9A of each pin mounting hole 9 and to be spaced apart in the left-right direction. Since it is formed to be thinner on the upper side (on the crown 2 side) and thicker in the left-right direction, it can easily follow the long piston pin 10 in which the amount of displacement is likely to be large due to inertial force or thermal deformation. Furthermore, since the semi-cylindrical portion 22 is formed in a semi-conical cylindrical shape whose thickness gradually increases from the outer surface 7B of the skirt portion 7 toward the inside, the rigidity is effectively reduced, and the semi-cylindrical portion 22 is elastically deformed. Can be done.

Next, a third embodiment of the present invention will be described with reference to FIGS. In this embodiment, the same components as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The recesses 31, 31 according to the present embodiment are formed in a downward C-shape on the outer surface 7B of the skirt portion 7 so as to surround each pin mounting hole 9 over a range of, for example, about 270 °. I have. Further, each recess 31 is separated above the outer opening 9A of each pin mounting hole 9 (above the offset center line XX in FIG. 3), and as it goes diagonally left and right below the outer opening 9A. It is formed so as to gradually approach.

Each recess 31 forms a cylindrical portion 32 which surrounds each pin mounting hole 9 in a substantially upward D-shape. Each of the cylindrical portion 32 is thicker outer opening 9A upper thickness t ₃ of each pin mounting holes 9, the thickness in the lateral direction along the horizontal line Hc-Hc passing through the axis center C of the piston pin 10 t
₄ is thinner, and furthermore, its horizontal line Hc-Hc
Is formed so that the wall thickness gradually increases again toward the lower side of the outer opening 9A of each pin mounting hole 9 beyond. Thereby, when the broach grooves 9B, 9B are formed in the pin mounting hole 9, the thickness around each of the broach grooves 9B is:
It is thinner than the thickness above pin mounting hole 9.

In this embodiment thus constructed, the same operation and effect as those of the first and second embodiments can be obtained with respect to the deformation of the piston pin 10 due to the inertial force and the thermal deformation. it can. In addition, in this embodiment,
The concave portion 31 is formed so as to gradually approach from the upper side of each pin mounting hole 9 to the left and right diagonally lower side, thereby increasing the thickness of the substantially D-shaped cylindrical portion 32 to the upper side (the crown portion 2 side). Since it is formed so as to become gradually thinner as it goes obliquely downward, the followability of the thin piston pin 10, which tends to increase in deformation due to “crushing”, can be further improved, and the surface pressure can be reduced.

In the first and third embodiments, the cylindrical portions 13 and 32 are formed such that the thicknesses thereof are uniform in the radial direction. However, the present invention is not limited to this. As described in the second embodiment, the radial thickness may be gradually changed to form a tapered shape. If the first embodiment is given as a representative example, the cylindrical portion 13 is formed in a tapered shape by gradually changing the thickness in the radial direction, and a modified example shown in FIG. 7 is obtained.

[0038]

As described in detail above, according to the piston of the internal combustion engine according to the present invention , each pin is provided on the outer surface of the skirt.
Separate from the mounting holes and surround each pin mounting hole around the pin mounting hole.
By providing a continuous recess over the entire circumference of the hole, rigidity around the upper portion of each pin mounting hole can be reduced, and deformation of the piston pin due to inertial force or thermal deformation. , The skirt portion between the pin mounting hole and the concave portion can be elastically deformed. As a result, when the piston pin is deformed, the surface pressure between both ends of the piston pin and the pin mounting hole can be reduced, sliding wear can be reduced, and the occurrence of seizure can be prevented. .

[Brief description of the drawings]

FIG. 1 is a front view of a piston according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG. 1 showing a state where a connecting rod and the like are attached.

FIG. 3 is a front view of a piston according to a second embodiment of the present invention.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3 showing a state where a connecting rod and the like are attached.

FIG. 5 is a front view of a piston according to a third embodiment of the present invention.

FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5, showing a state where a connecting rod and the like are attached.

FIG. 7 is a sectional view of a piston according to a modification of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Piston 2 ... Crown part 3 ... Ring land part 7 ... Skirt part 8 ... Pin boss part 9 ... Pin mounting hole 10 ... Piston pin 12, 21, 31 ... Concave part 13, 22, 32 ... Cylindrical part

Claims (3)

(57) [Scope of request for utility model registration] 1. A cylindrical scar provided under a crown.
And a pin provided opposite the inner surface of the skirt.
And a piston pin provided on each of the pin bosses.
Of an internal combustion engine provided with pin mounting holes for supporting both ends of the engine
Tongue, the outer surface of the skirt portion
Separate from the mounting holes and surround each pin mounting hole around the pin mounting hole.
A continuous recess is provided over the entire circumference of the hole.
Internal combustion engine piston. 2. A cylindrical scar provided on a lower side of a crown.
And a pin provided opposite the inner surface of the skirt.
And a piston pin provided on each of the pin bosses.
Of an internal combustion engine provided with pin mounting holes for supporting both ends of the engine
At the ton, on the outer surface side of the skirt,
A continuous recess around the perimeter of the hole is provided around the entire circumference of each pin mounting hole.
And a circle is formed on the outer peripheral side of the outer opening of each of the pin mounting holes.
A piston for an internal combustion engine, wherein a piston is formed. 3. A cylindrical scar provided below the crown.
And a pin provided opposite the inner surface of the skirt.
And a piston pin provided on each of the pin bosses.
Of an internal combustion engine provided with pin mounting holes for supporting both ends of the engine
At the ton, on the outer surface side of the skirt,
A continuous recess around the perimeter of the hole
Characterized by being formed with a depth dimension not more than the thickness dimension of the
Internal combustion engine piston.